Question

Describe how acyclovir works, and what virus(es) does it work against and How toxic it is?

Answer 1

Acyclovir is a common antiviral drug used against herpes simplex (type l and type ll), cytomegalovirus, varicella-Zoster. These viruses take this acyclovir and convert it into active triphosphate thus inhibiting viral DNA replication. It depends on the viral thymidine kinase for the phosphorylation to occur, so that they become active triphosphate.

Pharmacokinetics

• Absorption - It is a poorly absorbed drug, absorption is affected by the presence of food.
• Distribution - Widely distributed in all body tissues, fluids including semen, CSF, and brain tissues. Also, it crosses the placental barrier due to low protein binding.
• Metabolism - Metabolised in the liver
• Excretion - Excreted through kidney and has a half-life of 3hrs in case of humans.

Contraindication

During dehydrated states, earlier renal functional impairment, hypersensitivity, neurological deficit, etc.

Adverse effects

• During parenteral therapy, there is a chance for thrombophlebitis, acute renal failure, and ecephalopathological changes.
• During oral or parenteral therapy GI disturbance can occur.

Toxicity

• Concomitant IV administration with nephrotoxic medication increases nephrotoxicity potential. For example, with amphotericin B increases nephrotoxic potential.
• neuropsychiatric symptoms
• Viral encephalitis
• Tiredness and malaise
• Gi disturbance like nausea and vomiting